Nitride semiconductor materials (such as GaN, InGaN, AlGaN, InN and AlN), for example, gallium nitride, have a wide direct bandgap, a strong chemical bond, a high thermal conductivity, a good chemical stability and a great anti-radiation performance, which shows great potentials in applications of photoelectron, high temperature and high power devices and high frequency microwave devices, being widely used for fabricating various electronic switches and signal amplifiers.
The nitride semiconductor material generally has a close-packed hexagonal crystal structure. Based on a relative position between a surface of a wafer and c axis of the crystal, the surface may be classified as a polar surface (perpendicular to c axis), a nonpolar surface (parallel to c axis) and a semi-polar surface (neither perpendicular nor parallel to c axis) because of a spontaneous polarization effect. For example, in gallium nitride, a crystal plane of {0001} (also referred to as c-plane) is polar, crystal planes of {1010} and {1120} (also referred to as m-plane and a-plane, respectively) are nonpolar and a crystal plane of {1102} (also referred to as r-plane) is semi-polar. Currently, a GaN wafer with a polar c-plane is most widely studied and used, and there are few studies and applications about the nonpolar and semi-polar planes.
By using magnetron sputtering, atomic layer deposition and etc., dielectric materials may be deposited on a surface of the nitride semiconductor materials. Semiconductor structures with different dielectric/nitride interface characteristics may be fabricated and used in different semiconductor devices.
However, a design and a fabrication method of the dielectric/nitride interface structure based on the nitride semiconductor materials are still to be improved.